package zuoye;

import java.util.Scanner;

public class Test5 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        float sum = 0;
        for (int i = 1; i <= 12; i++) {
            sum += scan.nextFloat();
        }
        sum = sum / 12;
        System.out.printf("$%.2f", sum);
    }
}
